Cation Exchange Enabled Cu Dopants Location Tailoring and Photoelectric Properties Regulation in CdS Nanosheets

Doping-related point defect engineering in low-dimensional semiconductor nanostructures is important to regulate their optical and electronic properties. The substitutional or interstitial location of heterovalent dopants is critical and has not been controlled effectively yet. Herein, we carefully control the kinetics of reverse cation exchange between CuxS 2D nanosheets and ligand-coordinated Cd2+ cations to control the Cu doping sites in CdS nanosheets (NSs). The substitutional and interstitial Cu dopants were directly confirmed by spherical aberration-corrected TEM (SACTEM) and their X-ray absorption spectroscopy (XAS) coordination investigation. Density functional theory (DFT) calculations and their experimental conductivities and dopant luminescence performance demonstrated the dramatic differences that are due to the location of different Cu dopants. These findings provide deeper insights on dopants' location regulation in a nanostructured host semiconductor.